Ultrasonic diagnostic systems are widely used in medical fields as medical systems. Ultrasonic diagnostic systems are used in surgeries and treatments. For example, an ultrasonic diagnostic system is used to safely insert a puncture needle into a living body in order to retrieve tissues, inject medicine, treat tissues, or for other purposes. Specifically, a puncture adapter (attachment tool) is attached to a probe, and a puncture needle is set on the puncture adapter. A user inserts the puncture needle supported by the puncture adapter into a living body while viewing ultrasonic images. The puncture adapter is generally used to guide a puncture needle such that an insertion path is within a beam scan plane. A user inserts a puncture needle while viewing a target image (for example, a tumor image) and a puncture needle image in ultrasonic images. For example, insertion of a puncture needle is stopped when a tip of the puncture needle or its electrode portion reaches the center of a target such that a certain treatment can be performed under that condition.
In recent years, high-frequency medical treatments using two or more puncture needles have been started to be actually used. For example, two or more tips of puncture needles are positioned in a surrounding or vicinity area of a target such that high-frequency signals are supplied to electrode portions on the tips. In this way, medical treatment to cauterize a target is performed. As a puncture needle for such medical treatment, a bipolar-type treatment tool with a pair of electrodes is known. Positioning two or more puncture needles, for example, in parallel to each other with the tips aligned to each other in a living body is not an easy task. Realization of a system to assist such an operation is strongly desired.
It should be noted that, as a navigation technique or diagnostic assistant technique, techniques to display one or more reference images with an ultrasonic image (generally, a two-dimensional sectional image) are known (for example, Patent Literature 1). In those techniques, volume data obtained by an X-ray CT apparatus, an MRI apparatus, a three-dimensional ultrasonic diagnostic apparatus, or any other apparatuses are used. Based on the obtained volume data, images such as a three-dimensional image representing a three-dimensional space including the beam scan plane and a two-dimensional reference image representing the cross section corresponding to the beam scan plane are generated and displayed. In such a case, when a probe is moved, the ultrasonic images also change in accordance with the position and the orientation of the probe. The three-dimensional reference images and the two-dimensional reference images also change accordingly.